In Asch's (the Baby Bear books) latest picture book, Baby Bird falls out of her mother's nest one night and manages to return with the help of new friend Little Frog. The nest of the title refers to a new one that the two pals build together; it is almost immediately abandoned, but it helps Baby Bird get her first taste of independence. It also sets the stage for her later escape from a raccoon, as she hops to a tree branch, just out of the raccoon's reach. From there, Little Frog coaches her, by example, to make her way to her mother's nest (""Take it one hop at a time,"" he says). Asch's illustrations, done in pen and ink and then computer-colored, are skillfully done and infused with moonlight; they resemble intricate sun-catchers. The frog is a charmer, with expressive gestures and a bubble-gum-pink tongue; and a menacing close-up of the raccoon gives way to a pleasing image of Baby Bird hovering safely above the villain. A slim but reassuring tale for toddlers just beginning to strike out on their own. Ages 2-5. (May)